The Cirrus groups that effectively buy blocks of hours and the non-equity groups are a very different set up from spending a few thousand to buy into a motor glider group.
You pay relatively MORE to buy into the motor glider group on the assumption that you will get something back. (when I say you pay relatifully more - I mean the post above where some one seemed quite prepared to pay a premium above the value of the aircraft to buy in the group)
The non-equity groups you don't expect to get get anything back. Just pay for your hrs, and maybe monthly fees. Then walk away at the end.